Stand alone engine speed control at cold start for hybrid transmission

Method to start operation of an internal combustion engine of a hybrid powertrain, the hybrid powertrain comprising the engine, a battery, an electro-mechanical transmission including at least one electric machine rotatably coupled to the engine, the electro-mechanical transmission selectively controllably operative to transmit torque among the engine and the at least one electric machine, comprising:

• initiating rotation of a crankshaft of the engine with the at least one electric machine until a first predetermined crankshaft speed is achieved;
• firing the engine while controlling engine speed with the at least one electric machine until an occurrence of one of,
• a second predetermined crankshaft speed is achieved,
• a predetermined number of cylinder events is achieved, and
• a predetermined crankshaft acceleration over a predetermined duration is achieved;
• and
• during the firing of the engine
• increasing the engine speed based solely on controlling at least one of a spark induced torque of the engine and an airflow torque of the engine until a third predetermined crankshaft speed is achieved while operating the at least one electric machine in a relaxed state providing zero torque output to the engine and the energy storage device,
• reducing the engine speed once the third predetermined crankshaft speed is achieved based solely on controlling combustion parameters of the engine while operating the at least one electric machine in the relaxed state providing zero torque output to the engine and the energy storage device, and
• controlling the engine speed with the at least one electric machine while the engine is still firing subsequent to an occurrence of at least one of,
• a transmission range selector shifting to a drive state from one of a park state and a neutral state, and
• an engine coolant temperature achieving a predetermined engine coolant temperature and a battery temperature achieving a predetermined battery temperature.